Automotive power demands drive 48 V adoption

Automotive, like many industries, settled on a standard operating voltage years ago. However, standards evolve over time as technology advances. We can see this evolution of standards in the automotive industry.

The first cars had no electrical systems at all. They were started with a hand crank and lights were powered by oil. Then came the lead acid battery, followed by 6 V power. This worked for a while, but as engines got larger and more electronics were added, more power was needed. So 12 V became the new standard.

Today we are in the midst of another change. Automotive power demands are scaling rapidly, especially within autonomous vehicles. Artificial Intelligence in vehicles is also a major power driver. Power trains and infotainment demands are requiring significantly more power.

The 12 V battery is no longer enough. The next logical jump is to 48 V. This isn’t a difficult change right now as some cars are using a dual battery solution. They split the power delivery between a traditional 12 V battery and a 48 V lithium ion battery. This is likely just a transitionary period before cars standardize on 48 V.

48 V delivers higher efficiency across many industries

Other industries are seeing a transition to 48 V as well. There is a similar change happening in data centers. They are using legacy 12 V power buses and want to use 48 V power buses to more efficiently power their soaring power demands.

Power tools also have jumped up in voltage, increasing torque and making battery technology smaller. Now you can easily find 48 V tools. They may be more expensive, but they will hold a charge longer and deliver more torque. LEDs are another industry that sees the value of using 48 V-- especially on outdoor lighting where power demands are greatest. It allows their displays to be brighter, larger, and more efficient.

What is the advantage to the 48 V power?

48 V allows you to add more power with less switching losses. This is because there is less current going through the same amount of copper. This allows it to travel farther and power more things. 48 V receives a SELV (Safety Extra Low Voltage) rating, which means it is still safe and requires no special handling. It is below 60 V which is seen as the cutoff for safe-to-handle voltages. Furthermore, the cabling does not need extra shielding nor is in danger of overheating.

So why not jump to 48 V right from the start?

From the beginning the cost and size of a larger battery made it impractical. While high voltage has its advantages, it also has some limitations. The contacts for higher voltage systems need to be more robust and they cost more because corrosion will set in more quickly. But as technology has progressed, we have become better at minimizing those disadvantages. Now most infrastructure and designs are built for 12 V. Once a standard is developed, it may be challenging to try and get people to adopt something new since all their parts run off 12 V.

Today most of these systems are trying to bridge 12 V to 48 V. They are not trying to completely overhaul the infrastructure, but transition their architectures. For example, newer mild hybrid cars are dual battery, with a 12 V and a 48 V battery. Companies are making it so you don’t have to change your whole system at once; you can adopt the newer power structure as you go. So, as we transition to higher voltages we will need various parts throughout systems.

This is where companies like Vicor come in. They just released a great “bridge” part, the NBM2317. The NBM provides bidirectional 48 V to 12 V conversion with 98% peak efficiency at 800 W continuous and 1 kW peak power in a package less than 3.3 cm3. Vicor has a family of 48 V parts that help build your 48 V power chain, and help you transition to the 48 V infrastructure.

About this author

Ben Roloff, Associate Applications Engineer at Digi-Key Electronics, has been helping customers with all their microcontroller needs since 2016. He was born in 1991, a time when internet was unheard of in the home. Internet slowly became a thing as he went through school - so in a way, Ben grew up with the internet. It was his interest in computers that drove him to pursue an education in computer engineering and he holds a Bachelor of Science in Computer Engineering from the South Dakota School of Mines and Technology.